1. Field of the Invention
The invention concerns a thick matter pump with a drive motor, preferably an internal combustion engine, with at least one hydraulic pump, preferably a reversible pump having a variable displacement volume, which can be coupled with the drive motor, with two hydraulic cylinders connected to the hydraulic pump and controlled in counterstroke (push-pull manner), each coupled to a transport or conveyor cylinder, with a regulator for regulating the rotational speed of the drive motor and a regulating element associated with the hydraulic pump for regulating the displacement volume, and with a control module for setting the rotational speed of the motor and the displacement volume of the hydraulic pump.
2. Description of the Related Art
It is further known that in thick matter pumps of this type the conveyor cylinders can be alternatively coupled to a conveyor line via a pipe switch or shunt, wherein the conveyor line is routed along a distribution boom, which is hydraulically operable via a hydraulic pump, and is preferably in the form of an articulated boom.
In mobile concrete pumps it is known (DE-A 196 35 200) to use, in the pumping operation, the already present vehicle motor and the vehicle transmission for driving the hydraulic pump. For this purpose, a power drive transmission or distributor gear is generally provided in the cardanic shaft line of the vehicle, which can be selectively switched between vehicle propulsion and pump operation. During pump operation the transport or conveyance volume of the thick matter pump can be adjusted by varying of the rotational speed of the drive motor. It is further known (DE-A 195 42 258) to use, for the control of the hydraulic cylinders of the thick matter pump, a hydraulic pump with variable displacement volume. With a given motor rotational speed, the conveyance amount can be adjusted by regulating the displacement volume of the hydraulic pump. The known hydraulic pumps are preferably in the form of axial piston pumps with slant disks, of which the displacement volume can be varied by adjustment of the slant angle of the slant disk. The adjustment of the slant disk slant angle occurs for example via an adjustment cylinder, which for its part is controllable via a proportional valve. The pump operator thus has available to him therewith selectively two regulating means, each independent from the other, for adjusting the desired thick matter conveyance amount. In order to complete the pumping operation as quickly as possible, in practice the motor is frequently operated at maximum rotational speed, with the regulation of the amount being accomplished by adjusting the displacement volume alone. Therein it is not taken into consideration that the specific fuel consumption of the drive motor is dependent primarily upon the motor rotational speed, and that the high rotational speed also increases the sound emissions and exhaust gas emissions.